Apparatus and methods for reduction of vertebral bodies in a spine

ABSTRACT

A system for reduction of vertebral bodies (or vertebrae) various embodiments includes a reducer, and extender, and a hollow tube. The reducer couples to the extender, which in turn couples to an elongated member, such as a rod, and to a bone fastener assembly. The reducer allows reduction of the vertebral body incrementally, and by a desired amount. The reducer may include or may be used in conjunction with a holding device or holder in order to hold or keep the amount of reduction constant or steady once the desired amount of reduction has been obtained. The reducer may use one of several embodiments, including embodiments that use threaded assemblies or members, inclining members or wedges, offset cams, scissor jacks, and/or levers.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 14/223,119, filed Mar. 24, 2014, which is a continuation ofU.S. patent application Ser. No. 11/567,889, filed Dec. 7, 2006, nowU.S. Pat. No. 8,679,128, issue date Mar. 25, 2015, the completedisclosure of which is herein incorporated by reference.

TECHNICAL FIELD

The present invention generally relates to apparatus and methods usedduring a spinal surgical procedure. More particularly, the inventiveconcepts relate to spinal surgical procedure that use apparatus andmethods for reducing vertebral bodies.

BACKGROUND

Modem spine surgery often involves the use of spinal implants to corrector treat various spine disorders or to support the spine. Spinalimplants may help, for example, to stabilize the spine, correctdeformities of the spine, facilitate fusion, treat spinal fractures,repair annular defects, etc.

Spinal implant systems for a lumbar region of the spine may be insertedduring a procedure using a posterior spinal approach. Conventionalsystems and methods for such operations may involve dissecting andretracting soft tissue near or around the surgical site, which may causetrauma to the soft tissue, and extend recovery time.

Minimally invasive procedures and systems may reduce recovery time aswell as trauma to the soft tissue surrounding a stabilization site.During minimally invasive surgical procedures, often a reduction of oneof more vertebrae are indicated. A need exists for reduction apparatusand related methods that provide flexibility of operation, enhancedrange of reduction, and adaptability to the patient's anatomy.

SUMMARY

The disclosed inventive concepts relate to apparatus and methods forreduction of vertebrae or vertebral bodies. In one exemplary embodiment,an apparatus according to the invention includes a reducer, and anextender coupled releasably to the reducer. The reducer includes asleeve and a knob. The sleeve has a threaded portion. Similarly, theknob has a threaded portion that is in engagement with the threadedportion of the sleeve to provide reduction of the vertebra or vertebralbody.

In another exemplary embodiment, a system for reducing a vertebra orvertebral body includes an extender and a reducer. The reducer isreleasably coupled to the extender, and is configured to allowincremental reduction of the vertebral body.

Yet another exemplary embodiment relates to a method of reducing avertebra or vertebral body. The method includes moving incrementally onemember with respect to a second member. The first member is releasablycoupled to the vertebra, which results in the reduction of the vertebraor vertebral body.

BRIEF DESCRIPTION OF THE DRAWINGS

The appended drawings illustrate only exemplary embodiments of theinvention and therefore should not be considered or construed aslimiting its scope. Persons of ordinary skill in the art who have thebenefit of the description of the invention appreciate that thedisclosed inventive concepts lend themselves to other equally effectiveembodiments. Unless noted otherwise, in the drawings, the same numeraldesignators used in more than one drawing denote the same, similar, orequivalent functionality, components, or blocks.

FIGS. 1A and 1B show details of how a typical reduction procedure bringsinto alignment a misaligned vertebra.

FIG. 2A shows a system for a spinal surgical operation that uses areducer according to an exemplary embodiment of the invention.

FIG. 2B illustrates reduction of a vertebral body by operating thereducer shown in FIG. 2A.

FIG. 3 depicts a reducer according to one exemplary embodiment of theinvention.

FIG. 4 shows a top view of the locking handles and locking members ofthe reducer in FIG. 3.

FIG. 5 illustrates a cross-section of the exemplary reducer illustratedin FIG. 3,

FIGS. 6-13 depict a plurality of reducers according to exemplaryembodiments of the invention.

FIG. 14 shows a holding device according to one aspect of the inventiveconcepts for use with reducers according to the invention.

FIGS. 15-19 illustrate a plurality of attachment mechanisms according toexemplary embodiments of the invention.

DETAILED DESCRIPTION

The disclosed novel concepts relate to apparatus and methods forreducing vertebrae or vertebral bodies during minimally invasivesurgical procedures, for example, during a spinal stabilizationprocedure. Details of minimally invasive surgery are described in detailin U.S. patent application Ser. No. 10/980,675, titled “Instruments andMethods for Reduction of Vertebral Bodies,” attorney docket number7769US01, filed on Nov. 3, 2004, and incorporated by reference in thisapplication. Briefly, minimally invasive surgery uses apparatus such asguide wires, bone fastener assemblies, extenders, and sleeves, asdescribed in detail in U.S. patent application Ser. No. 10/980,675,referenced above.

During minimally invasive surgery, a reduction of one or more vertebralbodies is indicated. As persons of ordinary skill in the art who havethe benefit of the description of the invention understand, reductiongenerally refers to the replacement or realignment of a body part innormal position or restoration of a bodily condition to normal. FIGS. 1Aand 1B show details of how a typical reduction procedure brings intoalignment a misaligned vertebra.

More specifically, in FIG. 1A, vertebral body 90 is out of alignmentwith the rest of the spine and is to be returned to its originalposition via a reduction procedure. To do so, the surgeon constructs a“framework” or assembly that will serve as the alignment point. Thesurgeon constructs the framework with pedicle screws or other suitablefasteners and a rod or elongated member to bridge the “bad” (defectiveor diseased) segment or vertebra and anchoring to the two “good”(healthy and properly aligned) adjacent segments or vertebrae above andbelow.

The surgeon places fasteners or pedicle screws (collar 112 of thefastener assembly is shown explicitly) into the desired vertebralbodies, including the “bad” segment (labeled 90). Once in place, thesurgeon locates an elongated member or rod 104 in the adjacent bonefastener assemblies (e.g., screw heads), and fastens it with a closuremechanism (e.g., closure cap). The rod is contoured in a manner thatwill hold the proper alignment of the segments or vertebrae once thereduction procedure is complete.

To aid in the reduction, the surgeon uses one or more extenders. Becauseelongated member or rod 104 passes through the middle extender (labeled170) in the figure, which is in turn attached to the pedicle screw orfastener of the “bad” segment, the extender serves two purposes. First,the extender acts as a guide for the proper alignment of elongatedmember or rod 104 into the fastener assembly (e.g., screw head).

The extender also serves as a mechanism to “pull up” on the fastener orscrew and consequently the vertebral body until elongated member or rod104 is properly seated within the fastener assembly (e.g., screw head).As described below in more detail, this is done by “pushing”incrementally against elongated member or rod 104 with a hollow shaft ortube (see for example item 188 in FIGS. 2A and 213) while “pulling” upon extender 170 in a manner similar to a tackle being used to hoist up aload.

This incremental, controlled relative motion is achieved by reducer(described below in detail). As detailed below, one part of the reduceris releasably coupled to extender 170 via locking member(s), whileanother part of the reducer (reduction shaft 308) is coupled to shaft ortube 188, which is in turn anchored or coupled to elongated member orrod 104.

FIG. 1B shows vertebral body 90 in its reduced state. Note that it iscompletely or substantially aligned with the rest of the spine oradjacent vertebral bodies. At this stage, a closure mechanism is appliedthat will secure, fasten, or lock elongated member or rod 104 to thebone fastener assembly (e.g., to the screw head), and therefore fix theposition of the “bad” or reduced segment or vertebra 90 with respect tothe adjacent segments. Bone graft may be applied to aid fusing thesegments together while held in place with elongated member or rod 104and the bone fastener assemblies.

Conventional reducers have a number of disadvantages, such as relativelylimited range of operation, relative lack of adaptability to thepatient's anatomy (e.g., the patient's lordotic curve), failing to allowfor incremental reduction, and involving manual interaction by thesurgeon at all times or substantially all times, etc.

As described here in detail, the disclosed reduction apparatus andassociated methods overcome those limitations. For example, thedisclosed reduction apparatus and related techniques allow incrementalreduction without continual surgeon intervention, thus allowing forgradual tissue relaxation, provide relatively extended range ofoperation or reduction, provide quick-coupling capabilities, and adaptmore easily to the patient's anatomy.

FIG. 2A shows a shows a system 100 for a spinal surgical operation thatuses a reducer according to an exemplary embodiment of the invention.System 100 includes bone fastener assembly 102 (e,g., screw, collar, andclosure member (e.g., cap)), elongated member 104 (e.g., a rod),extender 170, sleeve or assembly 186, and reducer 300. Some details ofsystem 100 are provided in U.S. patent application Ser. No. 10/980,675,referenced above.

During minimally invasive surgery, extender 170 allows the surgeon tomanipulate bone fastener assembly 102 and to couple fastener 108 tovertebra 90. A distal end of an extender 170 couples to bone fastenerassembly 102 and allows the surgeon to manipulate assembly 102. In theembodiment shown, extender 170 couples to collar 112 of assembly 102.

After a bone fastener assembly is coupled to extender 170, a driver maybe coupled to a bone fastener of the bone fastener assembly. The drivermay be used to insert the bone fastener into vertebral bone, such asvertebra 90.

Elongated member 104 allows the surgeon to accomplish a desired goal,for example, stabilize the spine, maintain the natural spacing betweenvertebrae, etc., as persons of ordinary skill in the art who have thebenefit of the description of the invention understand. After bonefastener assemblies are installed and an elongated member is placed inthe bone fastener assemblies, closure members may be secured to the bonefastener assemblies.

When a closure member is threaded on a bone fastener assembly, a countertorque wrench may be used to inhibit the application of torque to thespine of the patient. A counter torque wrench may hold an extender thatis coupled to a collar. The counter torque wrench allows the applicationof an appropriate or desired amount of torque, for example, to shear offthe tool portion of a closure member.

In some embodiments, a counter torque wrench may inhibit application oftorque to a patient during tightening of a closure member and/or duringshearing of a tool portion of the closure member by applying a force toan elongated member to counter the force applied to a bone fastenerassembly by rotation of the closure member.

The counter torque wrench may take a variety of forms. For example, itmay constitute a sleeve that includes hollow shaft or tube 188. Hollowshaft 188 may be inserted through an opening in the body over extender170 and advanced toward the patient's spine.

Handle 190 of sleeve or assembly 186 may have of various shapes ordesigns, as desired. In some embodiments, a shape of handle 190 mayfacilitate gripping of sleeve or assembly 186 or hollow tube 188. Handle190 may include a cut-out portion to facilitate gripping and/or toreduce the weight of the sleeve. In certain embodiments, a shape ofhandle 190 may be tapered toward hollow shaft 188 to reduce interferenceand/or increase visibility of a surgical site.

In the embodiment shown, handle 190 includes lock button or mechanism191. During normal operation, lock mechanism 191 locks or holds theposition of handle 190 with respect to sleeve or assembly 186 or hollowshaft 188. By pulling back lock button 191, the surgeon may “flip”handle 190 around (i.e., move it along the path shown by arrows labeledA) in order to reduce interference with the (patient's body and/orincrease visibility of the surgical site.

In some embodiments, reducing one or more vertebral bodies to the shapeof an elongated member (e.g., a contoured elongated member) or to adesired position may be indicated. Reduction of a vertebral body duringa spinal stabilization procedure may include forcing or moving thevertebral body into a position determined by the contour of theelongated member used in the spinal stabilization system or by otherindicia.

During a spinal stabilization or implant procedure, a first portion ofan elongated member may be seated in a collar of a first bone fastenerassembly that is coupled to a first vertebra. A closure member may becoupled to the collar and the elongated member to seat the elongatedmember fully in the collar and to fix the position of the elongatedmember relative to the first bone fastener assembly.

A second portion of the elongated member may be positioned adjacent to acollar of a second bone fastener assembly that is coupled to a secondvertebra. The position of the second vertebra and/or the shape of theelongated member, however, may inhibit the second portion of theelongated member from being fully seated in the collar of the secondbone fastener assembly.

A reducer may be coupled to the elongated member and to the collar ofthe second bone fastener assembly (e.g., via extender 170). The reducermay be used to reduce the vertebral body, e.g., fully seat the secondportion of the elongated member in the collar of the second bonefastener assembly.

While the reducer holds the second portion of the elongated memberseated in the collar of the second bone fastener assembly, driver 101may be used to secure a closure member (e.g., cap or other suitableitem) to the collar to fix the position of the elongated member relativeto the collar. Radiological imaging or fluoroscopy may be used todetermine when the reducer has fully seated the second portion of theelongated member in the collar of the second bone fastener assembly.

Reducers may be used during a minimally invasive surgical procedure orduring procedures where access to an elongated member and working roomare restricted. During a minimally invasive procedure or a procedurewith limited access and/or limited working room, a reducer may be usedto pull an extender coupled to a bone fastener assembly of a spinalimplant or stabilization system upward (e.g., away from the spine) toseat the elongated member in a collar of the bone fastener assembly.Movement of a reducer may be achieved by, but is not limited to beingachieved by, use of threading, cam action, linkage arms, or acombination thereof, as described below.

In some embodiments, a reducer may be used with one or more otherinstruments to achieve reduction of a vertebral body coupled to a spinalstabilization system. FIG. 2A depicts an embodiment of reducer 300 thatmay be used in combination with extender 170 and sleeve or assembly 186,including hollow shaft 188.

The reducer may be used to seat elongated member 104 in collar 112 ofbone fastener assembly 102 when the bone fastener assembly is coupled toa vertebra. The reducer is designed to couple to extender 170 and pullit upward while pushing elongated member 104 into collar 112.

Without loss of generality, in one embodiment, reduction of vertebralbody 90 is accomplished by moving vertebral body 90 coupled to bonefastener assembly 102 relative to elongated member 104 in such a mannerthat the elongated member 104 is captured within collar 112 of bonefastener assembly 102, thus holding vertebral body 90 in desiredposition. The reduction is accomplished by inducing relative motion ofelongated member 104 with respect to collar 112 coupled to vertebralbody 90 via assembly 102 or vice versa.

An apparatus for inducing relative motion is reducer 300 with engagingtabs 306 and reduction sleeve 308 that moves with respect to engagingtabs 306. Engaging tabs 306 are coupled to extender 170, which in turnis coupled to vertebral body 90 via assembly 102. Reduction sleeve 308is coupled to hollow shaft 188, which in turn is coupled to elongatedmember 104. By manipulating reduction sleeve 308 with respect toengaging tabs 306, shaft 188 moves relative to extender 170. As aconsequent, elongated member 104 moves relative to collar 112 ofassembly 102, which is coupled to vertebral body 90.

Note that the reduction apparatus uses shaft 188 and the extender 170 inorder to “reach” through a small incision into the patient andmanipulate elongated member 104 with respect to vertebral body 90. FIG.2B shows elongated member 104 seated into collar 112 of assembly 102 asa result of operating reducer 300 (i.e., as a result of the reduction ofvertebra or vertebral body 90, as described below in detail).

FIG. 3 shows a reducer according to one exemplary embodiment of theinvention. Reducer 300 includes knob or handle 302, locking handles 304,locking or engaging members or tabs 306, reduction sleeve 308, and bore310.

FIG. 4 shows a top view of locking handles 304 and locking members 306.Locking handles 304 include or couple to a biasing mechanism, e.g.,springs to facilitate engagement of locking members 306 to extender 170.Depressing locking handles 304 causes locking members 306 to withdrawfrom openings in reduction sleeve 308. Releasing locking handles 304,however, causes locking members 306 to return to their originalpositions in the openings.

FIG. 5 shows a cross-section of reducer 300. Note that an inner portionor surface of knob 302 includes threads 312. An outer portion or surfaceof reduction sleeve 308 includes threads 314, which are complementary tothreads 312 of knob 302.

Once assembled, the threads of knob 302 engage the threads of reductionsleeve 308. By rotating knob 302 along the arrows labeled “B,” one maycause the coupled or engaged threads of knob 302 and reduction sleeve308 to cause sleeve 308 to move up or down or vertically, as the arrowlabeled “C” shows. The movement of sleeve 308 may in turn cause thecorresponding motion of other apparatus or items coupled to it.

During minimally invasive surgery, reducer 300 couples to other surgicalapparatus in order to reduce a vertebral body. For example, in oneembodiment, reducer 300 couples to extender 170 (see above) via lockingmembers 306. More specifically, by depressing locking handles 304, thesurgeon causes locking members 306 to withdraw or move in an outwarddirection (away from sleeve 308). The surgeon then couples reducer 300to extender 170 (e.g., by placing reduction sleeve 308 over or insideextender 170, as desired) and releases locking handles 304, as describedabove.

Once reducer 300 has coupled to extender 170, the surgeon may turn knob302 in a desired direction and by a desired amount. As described above,the turning of knob 302 causes shaft 188 moves relative to extender 170.As noted, extender 170 is coupled to the bone fastener assembly 102 (seeFIGS. 2A and 2B). Consequently, elongated member 104 moves relative tocollar 112 of assembly 102, which is coupled to vertebral body 90, hencecausing reduction of vertebral body 90.

By using relatively fine thread pitches, one may allow the surgeon tofine-tune the reduction of the vertebral bodies, as desired. Forexample, the surgeon may accomplish the reduction through relativelysmall or incremental steps. This approach provides the benefit ofallowing the affected tissue to relax and helps to reduce trauma.

Furthermore, under normal circumstances, the surgeon need notcontinually manipulate reducer 300. Put another way, the surgeon mayactivate reducer 300 by a desired amount (by turning knob 302 in adesired direction and by a desired amount). Once the surgeon finishesmanipulating reducer 300, it maintains the desired or final reduction.

FIG. 6 shows a cross-section of another reducer according to anexemplary embodiment of the invention, coupled to extender 170 andhollow shaft 188. The reducer in FIG. 6 includes knob 302 and body 320.Body 320 couples to extender 170 through any suitable or desiredmechanism, such as locking members 306.

Body 320 has a threaded portion 320A that engages a complementarythreaded portion 302A of knob 302. Body 320 couples to extender 170.Turning knob 302 clockwise or counterclockwise causes body 320 and,hence, extender 170 to move up or down relative to hollow shaft 188. Asa result, by turning knob 302 in a desired direction and by a desiredamount, the surgeon can reduce the corresponding vertebral body.

FIG. 7 shows a cross-section of another reducer according to anexemplary embodiment of the invention, coupled to extender 170 andhollow shaft 188. The reducer includes knob 302, upper body 322, andlower body 324. Upper body 322 couples to extender 170 through anysuitable or desired mechanism, such as locking members 306. (Note that,alternatively, or in addition, lower body 324 may couple to extender170, as desired, and as persons of ordinary skill in the art who havethe benefit of the description of the invention understand.)

Upper body 322 has a threaded portion 322A that engages a complementarythreaded portion 302A of knob 302. Similarly, lower body 324 has athreaded portion 324A that couples to threaded portion 302A of knob 302.Threaded portion 322A and threaded portion 324A have opposite threaddirections. For example, in the embodiment shown, threaded portion 322Ahas right-hand threads, whereas threaded portion 324A has left-handthreads.

Of course, as persons of ordinary skill in the art, who have the benefitof the description of the invention understand, one may use otherarrangements of threads. For example, in one embodiment, threadedportion 322A may have left-hand threads and threaded portion 324A hasright-hand threads.

Turning knob 302 clockwise or counterclockwise causes upper body 322 andlower body 324 to move in opposite directions. As extender 170 couplesto upper body 322 (or lower body 324, as desired), movement of upperbody 322 (or lower body 324) causes extender 170 to move up or downrelative to hollow tube 188. As a result, by turning knob 302 in adesired direction and by a desired amount, the surgeon can reduce thecorresponding vertebral body.

FIG. 8 shows a cross-section of another reducer according to anexemplary embodiment of the invention, coupled to extender 170 andhollow shaft 188. The reducer includes knob 302 and body 320. Body 320couples to extender 170 through any suitable or desired mechanism, suchas locking members 306.

Body 320 has a threaded portion 320A that engages a complementarythreaded portion 302A of knob 302. Turning knob 302 clockwise orcounterclockwise causes knob 302 to move relative to body 320. Note,however, that turning knob 302 does not change its position relative toextender 170. As extender 170 couples to knob 302, movement of knob 302causes extender 170 to move up or down relative to hollow tube 188.Thus, by turning knob 302 in a desired direction and by a desiredamount, the surgeon can reduce the corresponding vertebral body.

FIG. 9 illustrates a cross-section of another reducer according to anexemplary embodiment of the invention, coupled to extender 170 andhollow shaft 188. The reducer includes two progressively inclinedmembers or wedges 350 and 352. Progressively inclined wedge 350 couplesto extender 170 (via, for example, coupling members not shownexplicitly). Progressively inclined wedge 352 couples to hollow shaft188.

By turning progressively inclined wedge 350 in a desired direction andby a desired amount, while holding progressively inclined wedge 352stationary (or vice-versa), the surgeon can cause movement of extender172 and hence reduce the corresponding vertebral body. Note that one mayuse a variety of implementations of the reducer, as persons of ordinaryskill in the art who have the benefit of the description of theinvention understand. For example, one may use progressively inclinedwedges 350 and 352 that include steps (rather than a continuouslyinclining profile) of desired size or height, as desired. Using steppedwedges would allow incremental reduction in discrete amounts or steps.

FIG. 10 depicts a cross-section of another reducer according to anexemplary embodiment of the invention, coupled to extender 170 andhollow shaft 188. The reducer includes a “z lever” configuration orassembly. Specifically, the reducer includes base 364 coupled to hollowshaft 188, and body 320 coupled to extender 170 (e.g., through lockingmembers 306), lever bar 360, and truss 362.

Lever bar 360 couples at joint 367 to truss 362. Truss 362 couples tobase 364 at joint. Lever bar 360 forms a lever, with a fulcrum at joint366. The surgeon may lift lever bar 360, thus exerting downward force ontruss 362 through joint 367. Truss 362 in turn exerts downward pressureon base 364 and hence on hollow tube 188. Lifting lever bar 360 alsocauses the lifting of body 320 and thus extender 170. Consequently, bylifting lever bar 362 by a desired amount, the surgeon can reduce thecorresponding vertebral body.

FIG. 11 shows a cross-section of another reducer according to anexemplary embodiment of the invention, coupled to extender 170 andhollow shaft 188. The reducer includes base 372 coupled to hollow tube188, and body 320 coupled to extender 170.

The reducer further includes bolt or screw 370, whose threads engagewith threaded portion 320A of body 320. An end of screw or bolt 370couples to base 372. Slide pin 374 couples a portion of body 320(opposite or distal end from screw or bolt 370 in the embodiment shownin FIG. 11) to base 372. Slide pin 374 provides stability to themechanism and facilitates movement of body 320 with respect to base 372.

The surgeon may turn screw or bolt 370, which causes body 320 to movecloser to (or farther from, depending on the type of threads of screw orbolt 370 and threaded portion 320A) base 372. Because extender 170couples to body 320, movement of body 320 causes reduction of thecorresponding vertebral body.

FIG. 12 illustrates a cross-section of another reducer according to anexemplary embodiment of the invention, coupled to extender 170 andhollow shaft 188. The reducer includes a “scissor jack” configuration orassembly. Specifically, the reducer includes base 382 coupled to hollowshaft 188, and body 320 coupled to extender 170 (e.g., through lockingmembers 306), lever bar 386, screw or bolt 380, and lever bar 388.

Lever bar 386 and lever bar 388 couple to each other at joint 390A.Lever bar 386 couples to body 320 at joint 390B and to base 382 at joint390D. Similarly, lever bar 388 couples to body 320 at joint 390C and tobody 382 at joint 390E. By turning screw or bolt 380, the surgeon causesthe location of joint 390C to move through slot 320A and the location ofjoint 390D to move through slot 382A, thus lifting body 320 with respectto base 380.

As noted, body 320 and base 380 couple, respectively, to extender 170and to hollow shaft 188. Thus, the lifting of body 320 causes thelifting of extender 1170 and therefore reduction of the correspondingvertebral body.

FIG. 13 shows a cross-section of another reducer according to anexemplary embodiment of the invention, coupled to extender 170 andhollow shaft 188. Generally speaking, the reducer includes an offset cam(locking member 306) assembly.

The reducer includes body 390 coupled to hollow shaft 188 and disk 392coupled to extender 170. Disk 392 couples to one end of shaft 394, whichpasses through a bore or opening in body 390. Another end of shaft 394couples to handle or member 396. Note that, rather than separate pieces(e.g., disk 392, shaft 394, and member 396), one may integrate orcombine one or more of the components shown in FIG. 13. As merely oneexample, one may combine shaft 396 and disk 392 as one component.

Crank or handle 398 couples to member 396 and assists in turning shaft394 and, hence, disk 392. Disk 392 couples to extender 170 via lockingmember 306 (e.g., a cam). Locking member 306 has an offset location withrespect to shaft 394. Thus, turning shaft 394 causes the lifting ofextender 170 and, hence, the reduction of the corresponding vertebralbody.

Another aspect of the invention relates to holding devices suitable foruse with reducers according to various embodiments of the invention.FIG. 14 shows a cross section of an exemplary embodiment of a holdingdevice. One may use the holder in conjunction or in combination with areducer (e.g., the reducers in FIGS. 9, 10, and 13) in order to holdextender 170 in place (i.e., keep steady or hold constant the degree oramount of reduction).

The holder includes base 402 coupled to hollow shaft 188 and body 404coupled to extender 170. Columns or bars 408A and 408B coupled body 404to base 402. Body 404 may move along the length of columns 408A and408B. Columns 408A and 408B have ratcheting teeth 410A and 410B,respectively. Ratcheting teeth 410A and 410B allow upward movement ofbody 404, but prevent its downward movement. Thus, the holder allows thesurgeon to maintain a desired degree or amount of reduction once it isachieved.

The holder further includes release handles or members 406A and 406B. Byactivating or operating release handles 406A and 406B, the surgeon cancause the release of the ratcheting teeth 410A and 410B, respectively,thus allowing movement of body 404 with respect to base 402.

One may use a variety of mechanisms to couple the reducers according tothe invention with extender 170, as persons of ordinary skill in the artwho have the benefit of the description of the invention understand. Asone specific case, one may couple the reducer to the extender in areleasable manner, such that the surgeon need not reverse sonic of thereduction procedure steps in order to decouple or release the reducerfrom the extender. The following description provides some examples ofreleasable coupling mechanisms that may be used with the reductionapparatus described above.

FIG. 15 shows a cross-section of an attachment mechanism according to anexemplary embodiment of the invention. The attachment mechanism includeslocking members 306A and 306B, and screw or bolt 420. Locking members306A and 306B couple to extender 170, for example, through notches orother mechanisms in extender 170. Locking member 306A is stationary(e.g., part of the body of a reducer), but locking member 306B may movein response to force applied to it.

More specifically, by turning screw or bolt 420, one may cause it tocontact and exert force against locking member 306B. Force appliedagainst locking member 306B causes it to engage extender 170 and coupleto it. Thus, by using the attachment mechanism, one may securely couplethe reducer or other desired apparatus to extender 170 in order toperform the reduction procedure.

FIG. 16 shows a cross-section of other attachment mechanisms accordingto an exemplary embodiment of the invention. The apparatus shown in FIG.16 illustrates two locking mechanisms. The locking mechanisms may beincluded within housing or member 432, for example, the body of areducer.

One locking mechanism includes locking member 306A. Locking member 306Acouples to housing 432 via a joint or hinge 434. Hinge 434 allowslocking member 306A to swing or flip down. In this position, lockingmember 306A engages and couples to extender 170. Hinge 434 also allowslocking member 306A to swing or flip up. In this position, lockingmember 306A disengages or uncouples from extender 170.

The second locking mechanism in FIG. 16 includes locking member 306B andbiasing member or spring 430. Locking member 306B may slide withinhousing 432. When it slides towards extender 170, locking member 306Bengages and couples to extender 170. Conversely, when it slides awayfrom extender 170, locking member 306B disengages and uncouples fromextender 170.

Spring 430 exerts some force against locking member 306B, which causesit to slide towards and couple to extender 170. When one desires touncouple extender 170 from locking member 306B, one may slide away orpush back locking member 306B from extender 170.

FIG. 17 depicts a cross-section of an attachment mechanism according toan exemplary embodiment of the invention. The attachment mechanism inFIG. 17 constitutes an “iris type” of mechanism, and includes lockingmembers 306, ring 440, and handle or lever 444.

Turning handle 444 causes movement of locking members 306. Morespecifically, turning handle 444 in one direction (e.g., clockwise)causes locking members 306 to move towards each other, and thus engageand couple to extender 170. Turning handle 444 in the opposite direction(e.g., counterclockwise), however, causes locking members 306 to moveaway from each other, and thus disengage and uncouple from extender 170.

FIG. 18 depicts a cross-section of an attachment mechanism according toan exemplary embodiment of the invention. The attachment mechanism inFIG. 18 includes locking members 306, housing 460 (e.g., body or otherpart of a reducer), shaft 450, and handle 454.

Handle 454 couples to shaft 450 via hinge or joint 452. Engaging handle454, e.g., by pulling it towards shaft 450, causes locking members 306to move in one direction, for example, towards each other. As a result,locking members 306 engage with and couple to extender 170.

Disengaging handle 454, e.g., by pulling it away from shaft 450, causeslocking members 306 to move in the opposite direction, for example, awayeach other. As a result, locking members 306 disengage and uncouple fromextender 170.

Note that one may include in the apparatus shown in FIG. 18 mechanismsfor holding handle 454 in a desired position, as desired, and as personsof ordinary skill in the art who have the benefit of the description ofthe invention understand. Examples of such mechanisms include ratchets,holding clamps, etc.

FIG. 19 depicts a cross-section of an attachment mechanism according toan exemplary embodiment of the invention. The attachment mechanism inFIG. 19 constitutes a “collet type includes locking members 306, sleeves472, and engaging members 474. FIG. 19 shows one attachment mechanism inthe locked position (the right side of FIG. 19), and another attachmentmechanism in the unlocked position (left side of FIG. 19).

Each of locking members 306 may move around a respective joint or hinge474. Generally, moving sleeves 472 causes engaging members 472 tocontact locking members 306, form a collar or collet around them, andcause them to move. Movement of locking members 306 may cause them toengage and couple to extender 170, or to disengage and uncouple fromextender 170. Note that the apparatus in FIG. 19 allows the surgeon tocouple either side of the reducer to extender 170 independently of theother side.

As described, several embodiments of reducers according to the inventiveconcepts use threaded mechanisms or portions. By using a desired threadtype and/or pitch, one may provide reducers with desiredcharacteristics, as persons of ordinary skill in the art who have thebenefit of the description of the invention understand.

For example, by using a relatively fine thread pitch, one may produce areducer that causes a relatively small amount of reduction for a givenamount of activation of the reducer (e.g., turning knob 302 in FIG. 3),and vice-versa. As noted, by using relatively fine thread pitches, onemay allow the surgeon to fine-tune the reduction of the vertebral bodieswith a relatively high degree of precision.

Furthermore, by varying the size or length of the threaded portion, onemay produce reducers with desired characteristics. For example, arelatively long or large threaded portion would allow a relatively largereduction of the vertebral body, and vice-versa. This property allowsreducers according to the inventive concepts to overcome the limitedrange of conventional reducers.

Various modifications and alternative embodiments of the invention inaddition to those described here will be apparent to persons of ordinaryskill in the art who have the benefit of the description of theinvention. Accordingly, the manner of carrying out the invention asshown and described are to be construed as illustrative only.

Persons skilled in the art may make various changes in the shape, size,number, and/or arrangement of parts without departing from the scope ofthe invention described in this document. For example, persons skilledin the art may substitute equivalent elements for the elementsillustrated and described here, or use certain features of the inventionindependently of the use of other features, without departing from thescope of the invention.

1. A rod reducing apparatus, comprising: a screw assembly comprising: athreaded shaft with a controlling member at a proximal end thereof; anda threaded body engaged with the threaded shaft; a rod contacting memberengaged at a distal end of the threaded body; and a grasping elementhaving a distal end, a proximal end and a longitudinal axis extendingtherebetween, the distal end configured to grasp and detachably coupleto a bone fastener and the proximal end connected to the threaded shaftof the screw assembly; wherein the rod contacting member defines apassage configured to slidably receive the grasping element; and whereinrotation of the threaded shaft slides the rod contacting member alongthe longitudinal axis.
 2. The apparatus of claim 1, wherein turning thecontrolling member causes the rod contacting member and the graspingelement to move relative to each other in opposite directions.
 3. Theapparatus of claim 1, wherein the controlling member is a knob.
 4. Theapparatus of claim 3, wherein: turning the knob in a first directioncauses the rod contacting member to extend; and turning the knob in asecond direction opposite the first direction causes the rod contactingmember to retract.
 5. (canceled)
 6. The apparatus of claim 1, furthercomprising at least a first locking member coupled to the threaded shaftof the screw assembly and configured to selectively engage the graspingelement.
 7. The apparatus of claim 6, further comprising a secondlocking member coupled to the threaded shaft of the screw assembly andconfigured to selectively engage the grasping element, wherein the firstand second locking members are disposed on opposing sides of the screwassembly.
 8. (canceled)
 9. A spinal reduction assembly comprising: abone fastener configured to be coupled to a vertebral body; a collarconfigured to be coupled to the bone fastener, the collar including aslot for seating a rod; and a reducer configured to be coupled to thecollar to seat the rod in the slot, the reducer comprising: a screwassembly comprising: a threaded shaft with a controlling member at aproximal end thereof; and a threaded body engaged with the threadedshaft; a rod contacting member engaged at a distal end of the threadedbody; and a grasping element having a distal end, a proximal end and alongitudinal axis extending therebetween, the distal end configured tograsp and detachably couple to the collar and the proximal end connectedto the threaded shaft of the screw assembly; wherein the rod contactingmember defines a passage configured to slidably receive the graspingelement; and wherein rotation of the threaded shaft slides the rodcontacting member along the longitudinal axis.
 10. The apparatus ofclaim 9, wherein turning the controlling member causes the rodcontacting member and the grasping element to move relative to eachother in opposite directions.
 11. The apparatus of claim 10, wherein thecontrolling member is a knob located at a proximal end of the reducer,wherein: turning the knob in a first direction causes the rod contactingmember to extend; and turning the knob in a second direction oppositethe first direction causes the rod contacting member to retract. 12.(canceled)
 13. (canceled)
 14. The apparatus of claim 9, furthercomprising at least a first spring-biased locking member coupled to thescrew assembly and configured to selectively engage the graspingelement.
 15. The apparatus of claim 14, further comprising a secondspring-biased locking member coupled to the screw assembly andconfigured to selectively engage the grasping element, wherein the firstand second spring-biased locking members are disposed on opposing sidesof the screw assembly.
 16. (canceled)
 17. (canceled)
 18. The apparatusof claim 6, wherein: the grasping element comprises an outer channel;and the first locking member comprises a tab that is resiliently biasedinto the outer channel.
 19. The apparatus of claim 18, wherein the firstlocking member can be displaced via a button to overcome the resilientbias and linearly push the tab directly out of the channel to unlock thethreaded shaft from the grasping member.
 20. The apparatus of claim 18,wherein the first locking member can be displaced via a lever toovercome the resilient bias and rotate the tab out of the channel tounlock the threaded shaft from the grasping member.
 21. The apparatus ofclaim 18, wherein the threaded shaft comprises a pocket to retain thefirst locking member and prevent axial displacement of the first lockingmember.
 22. The apparatus of claim 21, wherein the first locking memberis rotatable within the pocket.
 23. The apparatus of claim 14, whereinthe locking member comprises a button having a tab resiliently biasedinto the grasping element, wherein pushing of the button moves the tabout of engagement with the grasping element.
 24. A rod reducer apparatuscomprising: a resiliently-biased attachment mechanism configured toselectively couple to an extender positioned within theresiliently-biased attachment mechanism; a rod-contacting tubeconfigured to be positioned coaxially with the extender; and a reducingmechanism comprising: a knob located at a proximal end of the rodreducer apparatus and coupled to the resiliently-biased attachmentmechanism; and a body threadedly engaged with the knob and engaged withthe rod-contacting tube.
 25. The rod reducer apparatus of claim 24,further comprising: a shaft extending downward from the knob, the shaftcomprising: an outer surface having external threading; and an internalsurface; internal threading located on the body to engage with theexternal threading; a locking member adjustably extending from theresiliently-biased attachment mechanism; and a spring to bias thelocking member away from the internal surface and toward the extenderwhen the extender is positioned within the resiliently-biased attachmentmechanism.
 26. The rod reducer apparatus of claim 25, wherein thelocking member comprises: a button slidably coupled to a housing of theresiliently-biased attachment mechanism; and a tab extending from thebutton and configured to engage the extender when the extender ispositioned within the resiliently-biased attachment mechanism; whereinthe spring biases the button such that the tab is biased into engagementwith the extender when the extender is positioned within theresiliently-biased attachment mechanism.
 27. The rod reducer apparatusof claim 25, wherein the locking member comprises: a first lockinghandle pivotably coupled to a housing of the resiliently-biasedattachment mechanism; and a first tab extending from the first lockinghandle and configured to engage the extender when the extender ispositioned within the resiliently-biased attachment mechanism; andwherein the spring biases the first locking handle such that the firsttab is biased into engagement with the extender when the extender ispositioned within the resiliently-biased attachment mechanism.